Tractor running gear



June 13, 1933. N. M. ERDAHL TRACTOR RUNNING GEAR 2 Sheets-Sheet 1 Filed May 6, 1930 i/dzew June 13,1933. N, M; ERDAHL v 1,913,705

TRACTOR RUNNING GEAR Filed May 6; 1950 2 Sheets-Sheet 2 Patented June 13, 1933 UNITED-STATES Ni-mam item-ligaments; wis'cou'snryrssieres roi iifcinit nr amne i -u ccmrmr, or Enemies, Wisconsin, Ai CLOltiQRlttttIONf QF WISCQILSISIBIi" Application filed Kaye, 1930; seriaino. 450,1esw.

t This invention relates to vehicles of the a pfair: 0f transversely pivoted atone end. to mainframe Withload lifting, mechanism on said frame adjacent the pivotalconnection, The object'ofgthe crawler units as ballast. Itc'onsists in ce tain features and elements of construction in combination as herein shown andidescribed and as indicated by the claims. in

iIn the.drewingstmdY j g V Figure" 1; is a side elevation,,showing rather. diagrammatically t a vehicle embodying the present. invention. 1 r

i it Figure 2 is a fragmentarylend viewin-elevation Withthe crawler unitsindicatedin relation .of i the il Figure iisa through the knuckle connections at the' end dotted 1 outline and with; t -portion of the [equalizing beam broken away to indicatethe supporting 3 spring ofthe mainframe toi-the supporting structurerof the crawlerunits. n i

t Figure 3; is; an enlarged vertical section taken substantially as: indicated" through the pivot of the equalizing beam at line Eli- 3 on Figure 9/.fl e i i. vertical transverse? section [of the equalizing beam; taken substantially as indicated at line 4- 4- on Figure 3. it

i r Figure is a uiagrammaueene el venth .40

a portion: (if the li ehicle illustrating of the crawler units traversn'ig au'up'ward projectioi'i in the road bed and showing the effect on theequalizing beam. e Figure 6 is a diagrammatic YEW in s de elevation, with the ma Qr port on of the vehicle shown in clotted outline and illustrating the main frame at its upward limit ofmoveinent with respect to the crawler units; Vehicles of the type-withwhich the presefit invention =is; ccncerned include awpair or units indicated at 10,

horiZontal axis-preferably at the driving :or floating endsof the crawler sp'e'ctive idlerandwdrivingiwheels of each of the crawleriunits is ayflexiblejbelt', 515,; of

the pivotal connectionsis :preferably sup?- Aported 1 yieldingly on the as herein shown, the; yielding it support; con

sists ofw a transverse zleaf-H spring; 17, cenof transversely spaced crawler inechani'sins r a g d. for: unportingtherebetween a main frame, 11, on which are carried a j power plant and other appurtenances. 1 The main frame; at one end"about a transverse end-stile other: ends ioft ithei,crawler units being free to float: under control of spring means, sogas to; permita limited amount of vertical movement oft-said free ends'of the crawler units for accommodation to: irregus ilarities 1n the road bed. As illustrated in theidrawings, each crawler :unit includes a driving Wheel; 12, whichris-inounted fdrrotation ,about a transverse-, horizontal aikile, 13,:WlIlCll:qELlSO YSGIVQS aszgthewaxis for the pivotal conneetionrbetween the main frame,

11, anduthe crawler unit, 10.; Atthe free units are idler; wheels 1.4,and trained around the methe 1 creeper shoeyP adapted to i-secilre jtradtionlwith the ground. '1 i crawler lunits; and

nected to the under, side of; the main: frame and having its outer; ends resting upon but 1 not positively engaged with the structural 1 supports ofi thecrawler.uinits which. are

herein; shown as a pairli iof .tran'sversely spaced longitudinally extending channel members, i 18, suitably connected and braced together inuanyconvenient manner. i \Vhen vehicles of this-l character areeinploy'ed as draftunits for pulling in a substantially horizontal direction they ordinanily experience no difficulty by reason of the :fact that the crawler units :are pivoted at' one end E with the ether; ends floating lfJOL HJCCOlTIITIOdatG irregularities in the road bed. But when theYmain' frame is with apparatus in the nature of a present invention sglS particularly directed tqthat class ofvehicles lot the FcraWleiL type "in whichthe; crawler unitsare pivotally connected to the vehicle provided derrick or this second-knuckle is pivotally a bolt, 31, (at an axis perpendicular to the 'ing block thus supporting shown onthe frame at the end adjacent the pivotal connection, it becomes necessary to insure a proper balance of the load being lifted by the derrick, to provide somep0s1- tive engagement between the remote end of the main frame and the floating ends of the crawler units, so that the weight of these crawler units may be employed as ballast for assisting in lifting greater weights by the derrick.

At the end of the vehicle remote from 'the'pivotal connection of the main frame to the crawler units I provide a transversely extending equalizing beam, 20, pivoted centrally about a horizontal longitudinally extending axis, 21-, in a'yoke formed by a pair of spaced transversely extending angle members, 22, secured to the under side of the main frame, 11. This equalizing beam, as herein shown, is a hollow member of rectangular cross section having each of its ends formed to provide 'a'clevis or yoke.

The hollow beam, 20, has mounted within it a block, 20*, secured to the beam as indicated by the riveted bolt, 20*, said block constituting reenforcement of the tubular beam at the pivot bearing, of which said reenforcbecomes a part.

Each of the yoke ends of said beam is pivotally connected at a longitudinal, horizontal axis by a bolt, 24, to a'block, -25, hereinafter referred to as the knuckle which is provided with a transversely-[horizontal and floating pivotal connection by means of a bolt, 26, to a pair of vertically extending parallel links, 27,- having vertical slots, 28, in which the bolt, 26, is engaged; The lower ends of each pair of links, 27, are pivotally connected byabolt,29, (parallel to the bolt, 26,) to a second knuckle, 30, which is disposed directly below the knuckle, 25; and

connected by bolt, 29, laterally and parallel to the bolt, '24,) to a and inwardly offsetlug, 32, of a bracket, 33, which is rigidly secured by meansof bolts and machine'screws, 35, to the top flange of the innermost or adjacent channel member, 18, of the crawler unit, as shown in'Figures 3 and l.

By reason of the slotted links, 27, the floating ends of the crawler units are .permitted a limited amount of vertical movement about thefixed pivotal connections of their driving ends, which allows for flexure of the spring, 17 and as seen in Figure 5, one of the crawler units (indicated in dotted outline) is shown traversing an upwardly protruding obstacle at C on the road bed.

Since the spring, 17 merely rests upon the members, 18, of the crawler units, the slotted links, 27 supplement the springs as a connection between the frame, 11, and the crawlers, 10, 10, whenever the load on the lifting mechanism at A tends to separate the main frame, 11, from'the crawlers. If the bolts, 26, by which the slotted links, 27, are connected to the frame, 11, were merely rigid, with the frame at each side thereof, it will be evident that the up-and down movement at the free end of either crawler, 10, would be limited by the length of the slot, 28, in the link, 27, so that in traversing vuneven ground as indicated in Figure 5, if one crawler should be lifted to bring the bottom of its slot, 28, in contact with the bolt, 26, itwould then tend to lift the main frame, -11, bodily, although the lifting strain would be'thrown wholly onthe one bolt at the rising side of the machine; This action is-avoided by the use of the equalizer beam, 20, which carries the bolts, 26, at its opposite ends. I

It will be understood that normally the front end of the main frame is yieldingly supported by the spring, 17 with the bolts, 26, at the ends of the beam, 20,-riding freely in the links, 27 adjacentthe lower ends of the slots, 28'; and when one of the crawlers is lifted or raised, as in Figure 5, the spring, 17 which is connected at itscenter to the main frame, 11,acts as a lever for raising said frame; theupwardmovement of the main frame being about half the amount of movement of the raised crawler. When'one crawler is lifted so highthat its approach to the frame brings the lower end of the slot, 28, into engagement with the bolt, 26, a further rangeof upward movement is still permitted by the rocking of the beam, 20, which swings the opposite end of the beam downward so as to'carry its otherbolt, 26, downwardlyin the slot, 28, of the link, 27', associated with the other crawler. Then the equalizer beam, acting as a lever on which the frame, 11, is supported at'21, will raise said frame; but even then the frame, 11, being supported at the mid-point of the beam, 20, is lifted by only one half the amount of this additional upward movement of the crawler. j I

However, when the load on the frame is so great astosovercome the spring, 17, the additional load unsupported by said springwill be carried by the bolts, 26, engagingthe bottom of the slots, 28, of the links, 27. Thus, when one of the crawlers is raised, both the beam, 20, and spring, 17,

act as levers to raise the main frame; and I In most cases in which the lifting'strain at A tends to raise the opposite end of the frame, 11, the equalizer beamQQO, will pick up both crawlers simultaneously after. the frame, 11, has tilted upwardly far enough to take up the play in the slotted links, 27, and this is the primary function of said links. The action of the equalizer, "however, causes the links to interfere less with i a pivot on which it is supported at one end on said crawler units, and spring means located at a distance from said pivot and arranged for yieldingly, supporting the other end of the frame on said crawler units; a

end of the frame remote from the pivot, and

means positively engaging the ends of said beam with the respective crawler units, said means being constructed and arranged for permitting a limited range of vertical movement of' the crawler units relative to the frame and independently of each other; said last mentioned means including a knuckle pivotally connected to each crawler unit for swivelling about 'a horizontal longitudinal axis, and upwardly extending link members having floating connection with the ends of l the beam and having their lowerends piv otally connected to said knuckles about transverse axes.

2. In a vehicle, the combination with a pair of transversely spaced crawler units, a frame pivotally supported at one end of the crawler units, and spring means located at a distance from the pivot support and arranged for yieldingly supporting the other end of the frame on the crawler units, of a nection to said block at a horizontallongitudinal axis.

3. In the construction defined in claim 1, said beam having a pivot connection with the frame and being of hollow tubular formationand having a bearing block secured therein provlding reenforcement for the pivot connection of the beam to the frame.

NICHOLAI M. ERDAHL.

transversely disposed beam carried on the transversely disposed beam pivotally mounted at the end of the frame remote from the pivotsupport about a horizontal axis paral lel to and adjacent the longitudinal center 1 of the vehicle, and means connecting the ends of the beam with the adjacent ends of the crawler units, and arranged for. permitting a limited range of vertical movement of the adjacent ends of the crawler units independently of each other, each of said connecting meansincluding a knuckle pivotally connected to a crawler unit for swivelling about a horizontal longitudinal axis, apair of transversely spaced upwardly extending slotted link members pivoted at o e their lower ends to the knuckle at an axis transverse to that of the knuckle pivot, a

block pivoted between the pair of links and vertically movable therebetween and having its pivot engaged in said slotseach endof sald beam being forked tostraddle at least one of the links and having a pivotal con 

